Atmospheric pressure dyeboarding process

ABSTRACT

The dyeing of textile materials by first contacting the same with a liquid dye bath which may be either aqueous or essentially nonaqueous and which is maintained at an elevated temperature and then passing the dyed textile goods through a bath of molten metal maintained at a sufficiently elevated temperature that the aqueous portion of the dye bath liquid retained in the goods is converted to vapor and is completely reacted with the goods before the dyed goods leave the bath of molten metal, whereby the goods are expeditiously dyed and the dye liquid is completely exhausted without recourse to the use of superatmospheric pressures. Furthermore, the spent dye liquid no longer presents a pollution problem in the form in which it is discharged from the process.

United States Patent [72] Inventor Martin S. Maltenfort Blue Ball Road, Route 3, Elkton, Md. 21921 [21] Appl. No. 837,874 [22] Filed June 30, 1969 [45] Patented Jan. 11, 1972 [54] ATMOSPHERIC PRESSURE DYEBOARDING PROCESS 3 Claims, No Drawings [52] U.S.Cl 8/18, 8/130.1, 8/17, 264/346 [51] Int. Cl 006p 5/00 [50] Field ofSearch 8/130.l, 1,

[56] References Cited UNITED STATES PATENTS 1,377,517 5/1921 Novatny 264/347 2,102,794 12/1937 Gibbs 28/1 2,125,827 8/1938 Turkington. 8/1 UX 2,663,612 12/1953 Gibson 8/176 X 11/1954 Hannay et a1 8/34 OTHER REFERENCES White, American Dyestuff Reporter, July 3, 1967, pages 59l-597,TP890A5l2 Primary Examiner- Donald Levy Attorney- Lawrence 1. Field ABSTRACT: The dyeing of textile materials by first contacting the same with a liquid dye bath which may be either aque ous or essentially nonaqueous and which is maintained at an elevated temperature and then passing the dyed textile goods through a bath of molten metal maintained at a sufficiently elevated temperature that the aqueous portion of the dye bath liquid retained in the goods is converted to vapor and is completely reacted with the goods before the dyed goods leave the bath of molten metal, whereby the goods are expeditiously dyed and the dye liquid is completely exhausted without recourse to the use of superatmospheric pressures. Furthermore, the spent dye liquid no longer presents a pollution problem in the form in which it is discharged from the process.

ATMOSPHERIC PRESSURE DYEBOARDING PROCESS This invention relates to the dyeing and setting of hosiery and other textile products. More particularly, it relates to procedures whereby such processes may be carried out at atmospheric pressure, expeditiously and in an automatic manner.

In one presently known procedure for automatic dyeboarding as it is presently practiced, stockings are put on forms, the forms are conveyed into a pressure cabinet where they are dyed under superatmospheric pressures by spraying dye liquid onto the hosiery while it is subject to superatmospheric pres sure in the cabinet. The dyed goods are then exposed to steam at temperatures equal to or higher than the temperature at which dyeing was accomplished, after which they are dried.

In other known procedures, the hosiery is dyed and then steam treated at the same temperature.

ln another known process described in US. Pat. NOs. 2,693,995 and 3,077,370 and others, material to be dyed is passed through an aqueous dye liquor containing vat and sulfur dyes and then into a bath of molten metal maintained at a temperature below which any substantial ebullition of the aqueous dye liquid occurs.

The present invention departs from such prior art processes particularly with reference to the temperatures of the dye liquor, the compositions of the dye liquor and the temperatures of the molten metal bath.

The process of the present invention presents a number of advantages and distinctions from such prior art processes in which a molten metal bath has been utilized for the treatment of textile materials.

When a molten metal or alloy bath constitutes the heating medium, a number of advantages are obtained, including rapid and uniform heating of the goods being treated, the mo]- ten metal tends to keep the dye liquid in physical contact with the goods, since the dye liquor is incompatible with the molten metal especially when the dye liquid becomes a vapor, as it does when heated to a sufficient temperature, the temperature of the metal bath.

In one aspect of the present invention, the hosiery is put on a form and is dyed at a high temperature, e.g. above about 160 F., in a dye bath which contains water or above about 212 F., in a dye bath containing only a small amount of water. The boiling point of the dye bath is required to be lower than the boarding temperature. Suitable dye bath compositions include, in addition to somewhat limited amounts of water, polyhydric alcohols, disperse or other dyes, solvents, wetting agents, finishing agents and the like, as described in the illustrative examples which follow.

The following description of preferred embodiments of this invention is to be considered as illustrating the same and is not intended to limit the invention in any way.

ln the practice of the present invention, as it would be applied to hosiery, for example, the hosiery may be dyed continuously in either of two ways.

For hosiery which must be boarded to shape, stockings must be placed on boarding forms. These forms must retain their integrity at the temperature of the molten metal alloy bath and the forms must be nonreactive with the molten metal alloy bath. Polytetrafluoroethylene and polychlorotrifluoroethylene are examples of plastic materials which may be used. Aluminum and stainless steel are acceptable metals which may be used. Forms dressed with hosiery are immersed in the dyebath for 30 seconds to 1 minute. To assure uniformity, either the dye liquor can be agitated or the forms can be moved in the liquor so as to continually bring fresh dye liquor into contact with the goods being dyed.

For processing stretch" hosiery or other goods which do not have to be boarded, the hosiery or other goods can be dyed without forms simply by attaching the goods to clips on a cable propelled through the dye liquor and out again with an immersion time of from l to 1 minute, or the goods to be dyed may be held flat between moving open mesh conveyor belts which carry the hosiery or other goods through the dyebath. Immersion time is from A to 1 minute. The mesh is sufficiently open to permit intimate contact of the dye liquor with the goods to be dyed. Movement of the goods through the dye bath eliminates the need for agitation. Any suitable means for conveying materials to be dyed through a dye bath either on forms or in an unboarded condition may be used.

Either before or following dyeing, hosiery is traditionally boarded at 235 to 243 F. for type 6 nylon and at 250 to 260 F. for type 66 nylon. This is done by placing dyed hosiery on boarding forms having the shape of finished stockings and subjecting them to saturated steam at the appropriate temperature to cause the stretch oriented yarn to relax until it shrinks to fit the form. Cooling before stripping causes hosiery to retain the shape of the boarding form. Dry heat dehydrates the nylon; therefore, saturated steam is almost always used in boarding. It will be apparent from the high temperatures involved that boarding must be done batchwise in heavy vessels under pressure and as a result no continuous commercial process has been developed.

In the present invention, post-boarding is accomplished at high temperatures, e.g. 2050 F. higher than the temperature in the dyeing step, and at atmospheric pressure, by immersing the boarding form, with the freshly dyed hosiery on it, into a melt of low melting bismuth alloy, Woods metal or similar alloys. The essential temperature requirement of the molten metal bath is that when the form is removed from the melt of low-melting metal alloy, the form is hotter than the boiling point of the dye liquor. As a result, any dye liquor remaining on the goods flashes off as a vapor when the boarding form is withdrawn from the molten metal bath and hence no drying is required subsequent thereto. The vaporized constituents comprising the dye bath can be condensed and recovered, if desired, in order to improve the economics of the process.

The present invention permits continuous or batchwise boarding or setting of hosiery at elevated temperatures in an atmosphere of saturated steam without the need for complex and expensive pressure vessels.

This is achieved by boarding or setting the goods in a bath of low melting metal alloy such as the bismuth alloys sold as Cer robend which melts at 136 F. or as Cerrosafe which melts at -190 F. The alloys used must have a melting point below the temperature of the dyebath so that wet hosiery entering the body of molten metal will not freeze" the metal. The alloy bath must be maintained at a high enough temperature to effect boarding or setting of the dyed goods.

Hosiery or other goods enter the alloy bath on boarding forms or on the conveyor mentioned previously. The wet" goods from an essentially aqueous dye bath are at a temperature of 210 F. or below, while goods from essentially nonaqueous dye baths may be higher. The alloy bath being at 235 to 260 starts to heat the wet" goods, and the liquid present vaporizes, any water present turns to steam. The steam or other vapor which forms is incompatible with the molten alloy and, therefore, stays in contact with the goods. The vapors rapidly reach the alloy bath temperature of 235 to 260 F. without the need for external pressure. The dyed goods, therefore, by being in contact with hot saturated steam, are satisfactorily boarded or set in from 5 to 10 seconds.

Upon emergence of the goods from the bath, the hot vapors flash off into the air where they may be exhausted or condensed for reuse. After the vapors have flashed off, a completely dry stocking remains.

Furthermore, it has been found that the goods leaving the dyebath are wet with liquor containing unexhausted dyes. lt has been found that dyes continue to exhaust to completion during the vaporizing cycle, and since all parts of the goods are wet with dye liquid and heated approximately equal, unlevel dyeing does not occur.

Continuous exposure of the molten alloy bath is detrimental as oxidation produces a scum on the surface. In addition, hosiery processed without coating the fibers with a finish are flimsy and have poor snag resistance. To avoid these difficulties a film of a low melting waxy or resinous material is floated Disperse Blue 3 C.l. 6l505 on the molten alloy to prevent exposure to or contact with the air. Goods entering and leaving the bath through this layer will be thoroughly coated with wax or resin upon vaporization of the dye liquor and this further enhances the product.

Many materials, such as high molecular weight glycols, may form the air insulating layer on the surface of the alloy bath. However, I prefer to use a stearylamine containing 50 mols of ethylene oxide sold under the name of Ethomeen 18/60. This is a waxy product melting at 1 10 F. which is cationic. The cationic nature of Ethomeen 18/60 causes it to coat the fibers with a uniform film, imparts a smooth waxy hand to the hosiery and, because it is cationic, the stockings have the additional advantage of being antistatic.

The following are two exemplary formulations of dye baths which may be used in the present process, although many other well known dye baths may also be used without departing from the teachings of the invention.

An aqueous dyebath composition which will thoroughly scour and dye sheer nylon hosiery in 1 minute or less is as follows:

Disperse Red l C.|. l l I 10 Relative Proportions as needed for Disperse Yellow 3 Cl. H855 Correct Shade 12 mol polyethoxyalkyl phenol surfactant*l g./gallon low foaming nonionic alkyl aryl polyether surfactant** l g./gallon water to make I gallon A nonflammable solvent based dye bath composition containing only a very small amount of water is as follows:

Relative Proportions as needed for Disperse Red 43 C.l. 26l05 correct shade Disperse Blue 27 C.I. 77520 Disperse Yellow l2 C]. 24895 12 mol polyethoxyalkyl phenol surfactant*l g./gal. solvent low foaming nonionic alkyl aryl polyether surfactant**l g./gal. solvent Water-2O g./gal. solvent Solvent to make 1 gallon (The solvent may be trichloroethylene; perchlorethylene; l, l l

- trichloroethane; other possible solvents include hydrocarbons, alcohols, glycols, esters and ketones).

From the preceding description, the following advantages of the present invention are believed to have been made apparent:

1. Dyeing is rapid, less than 1 minute as compared with l to 2 hours in conventional rotary tubs. Automatic dyeboarders can accomplish the same rapidity, but only in expensive pressure vessels with high-pressure pumps.

Hyonic PIE-I20,

" Triton CF-2 l 2. The dyeing process does not generate waste liquor, as contrasted with one presently known automatic dyeboarder which discharges 13 gallons of effluent for every 60 stockings processed.

3. The process requires little heat, for once the system is at equilibrium the only heat needed is to make up heat losses from the tanks and to heat up added dye liquor and the hosiery being processed. In a dyeboarder or tub, all water must be heated every cycle as it is dumped usually after each cycle.

4. The invention requires no steam boilers. It is known in the hosiery industry that hosiery and boarding forms are continuously ruined by boiler carryover, steam condensate or boiler chemicals contacting hosiery and forms during the steaming cycle.

5. Since no superatmospheric pressure is involved in the process of the present invention, hence no heavy pressure vessels, seals, pumps, etc., required of pressure dyeboarding are used.

6. The invention offers flexibility over prior art automatic dyeboarding processes, since high production rates are maintained in which the hosiery may either be boarded or simply relaxed.

7. The invention provides flexibility in the application of finishes to hosiery as this is preferably done in a step completely separate from the dyeing step.

8. The invention produces dry hosiery without the need for a separate drying step, as is necessary with rotary tub dyeing or with automatic dyeboarding.

9. Other advantages and economies of operation will undoubtedly be apparent where particular operating conditions exist.

Having now described preferred embodiments of the invention, it is not intended that it be limited, except as may be required by the appended claims.

I claim:

1. A process in which a heat settable textile is set, which comprises:

uniformly heating said textile while wet with an aqueous dye liquor, by passing said wet textile through a bath of molten metal maintained at a temperature of at least about 235 F. and above the boiling point of the aqueous liquor with which said textile is wetted, thereby causing said textile to be set in an atmosphere of steam, evolved when the aqueous liquor on said textile is vaporized when said textile is immersed in said molten metal.

2. The process of claim 1 wherein the textile being processed is on a form while it is being processed.

3. The process of claim 1 wherein the textile being processed is withdrawn through a layer of wax or resinous material superimposed on at least a portion of the bath of molten metal. 

2. The process of claim 1 wherein the textile being processed is on a form while it is being processed.
 3. The process of claim 1 wherein the textile being processed is withdrawn through a layer of wax or resinous material superimposed on at least a portion of the bath of molten metal. 